Had a cruiser pull that in Merritt Island. Nobody could take a shower, fill their tanks because of no pressure, no volume. After we keel hauled him he was forced to get the hell out of the marina.

Mule I 100% agree. It totally mucks up the legit use of the dock fresh water supply. As I said this should only be used for testing purposes or in a real pinch and very limited. Some people don't care about their slip neighbors. These types need to be shown the exit...

As far as the original poster I'd redo the AC water pump plumbing getting rid of potential air locks otherwise you should expect the same results, a failed AC fresh water pump.
I have often wondered if you could do a close system for the AC cooling water effectively giving yourself a source for hot water? Then again it would be too complicated and it would require having a dedicated fresh water tank for the AC units and a way to replenish the water used. The more I think about it the more I'm convinced that's a bad idea.
Bill

Ron...that Dometic pump you suggested IS a March Pump...the same he is trying to get away from. I am going to give a write up about this company on this thread. I TRULY HATE THEM!!! in a bit I will tell ya how I really feel.

There were 2 pumps in the link one is the same as mine. It is a magnetic drive and there is no way that water can get into the motor unless the boat sinks. In 5 years the only problem I've had is the ceramic shaft that turns the impeller broke, I rebuilt it, all new parts for around $80.00. Mine runs 24/7 from mid June thru mid September, 1 pump for 2 units and at least 1 unit is always on, I'am reasonable certain it's the original pump from 1987. Maybe the build quality on pumps built now is not as good.

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Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.

One pump went hot, would cut out then ac would shut down because of no circulation. I imagine the cooling loop of copper inside the epoxy molded base went bad, likely the same on number 2 where the pump would run then jam. Free up the shaft and it would run then 15 min later again. shaft surged. in all cases I disassembled to component level...as far as I could and there were no impeller issues. There are no air into the system leaks, all double clamped with good hose...on both boats. Yeah, I own 2...want a really great Mainship 34 1982/2013 for less than 1/2 what I have in.
The above was #1 and #2, number 3 is in Mainship and still working. Number 4 quit pumping, being on an enforceable warranty I looked at the impeller, all OK and headed to West. Number 5 is in New Boat and I am cool, wife is not as mean. I am waiting for the next shoe to drop. Seems to me $300. a year for raw water pumping for air conditioning is a bridge too far. I will be buying the $750. pump mentioned above when the rest of the Marches and warranties are gone. Hell it is only 110vac mermaid 16500 btu unit, has a big Gtocco strainer. I only ask that the things do their job.

Be careful going to a larger pump. This was discussed a year ago. Here are 2 posts where too large a pump (s) caused failures.

"So I started looking for a replacement. I noticed that Mermaid published min. and max flow rates for their units. I had not seen max flow rates on any other site, so I called Mermaid tech support and was given this answer - “too much water results in turbulence and if there is any grit in the water it’s like a little sand blaster. It takes a while but you end up with little holes.”

Next I called Aqua Air and got the exact same answer."

I went down into the engine room and looked at the pump name plate for the first time - 1000 gal per hour - double the recommended upper limit by both suppliers.-----------------------------------------------------------------------------------"That's it. There doesn't have to be any grit, the high velocity will erode the tubing walls all by itself. If there is any contamination like a tiny barnacle sticking to the side of the tube it will create a cavitation bubble behind it that will fairly quickly bore a hole in the tubing wall and put seawater in the refrigerant that will instantly destroy the compressor."

Yes the pump has to be right sized to the system; bigger is not better.

March has an excellent reputation with many many users that recommend them after years of trouble free use.

That's one of the big benefits dealing with Depco, they know this subject inside and out and I can testify they really stand behind and support the products they sell. Their repair and refurbishment work is beautiful as well.

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George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"

I'm away from the boat right now and I can't recall the model, but the A/C needed 280 GPH and the pump was more than that. Right now, it's leaking through the motor side where the power cord enters. As far as pump conditions, I don't know how much better it can get. I pulled off the top of the strainer (which was clean) and had to get the top back on quickly. Both thru-hull and strainer are deep below waterline, and the water is only pumped maybe 5 ft. maximum with no dip and maybe 2 ft. vertical to the A/C. I've never been underway with A/C on and have thru-hulls cleaned regularly. Stream out the exhaust side is consistently good, even now, but how long is a pump going to last when it's leaking out of the motor housing?

Maybe Parks (Hopcar) can get me a super deal on the Rolls Royce of pumps. Thanks for the great feedback guys. Mule....I feel your pain, unfortunately.

Well, my AC does fine and I am using the recommended 500 gallon per hour pump, on both units. I can see how sand blasting could be an issue for the AC but right now I am fuming over the lack of concern from a company that was considered the benchmark after $1500 worth of pumps have passed through my ownership. I will be dealing with deco for ANYTHING but a March.

The $750 Oberdorfer mentioned is a great pump, there is one, (104M) feeding the 5 systems on my Hatt; lasted about 30 years until killed by an OS problem (operator stupidity); however I don't think they make anything that replaces the March appropriately, and the magnetic drive system of the March is in some ways superior, though replacing seals and impeller is easy (Depco sells a kit). I also had an Oberdorfer DC oil change pump, both units built like the proverbial tank and priced accordingly. They are also the OEM maker of the larger Cruiseair pumps. and are about 200 bucks cheaper when bought from Depco with the Oberdorfer label.

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George

"There's the Right Way, the Wrong Way, and what some guy says he's gotten away with"

Had March shown some concern, their rep followed up I would feel differently but their lack of concern is total disrespect and shows contempt for their customers. I am an angry, disappointed, disgruntled but good customer what with owning 5 of their pumps....I have done my part with my money and am entitled to have and broadcast the treatment received from these yahoos.

Based on your posts it's unclear, to me at least, as to whether you ever contacted March directly? Did you? And if so what did they say?

God knows I tried. The best I could do was deal with a factory Rep named Bob Esterbrook. E mails flew until it dawned on me he either had NO influence with the company or was lying. Had to be one or the other. If I had someone working for me and he makes a recommendation that just a replacement motor, costing me less than $150, in the name of customer service I would ship it. The e mail address got me to Bob, never could get to the company. After this stringing me on for months I would have rather they just told me to kiss their Rosie red. Like I said, an unethical company, total disregard for their customers, contempt even.
I am retired, own no stock in any competing company. Have no ties or financial upside in bad mouthing March except for the aggravation they have caused. I have all the e mails and I can post if there is any doubt.

My experience on 2 different boats with March pumps is the pumps were mounted in the bilge below the waterline. This type pump circulates water and doesn't pump it like a displacement pump. They will not prime themselves or pump against much head pressure, and I'am sure that they won't run dry very long without damage. If mounted above the waterline when the pump is shut off the water in the hose from the strainer to the pump would drain down to the water level leaving a air gap and this style pump will not move air. In the spring I sometimes have to push all the air out of the lines after winterizing by using a hose to push water thru the discharge thruhull.

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Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.

I have never had any luck by reverse flowing water from a through hull discharge fitting. I usually simply losen the clamp from one of my 2 AC fresh water feeds and crack it enough so water starts spiting a steady stream then I push the hose back on the pump and tighten the clamps. By now the water is flowing fine through both discharge fittings. It's a mater of breaking the air lock once I do that I'm good for the rest of the season baring no haul outs.
Bill

In all my cases strainer, pump both below the waterline and with seacock open water flows into the strainer. I also, just for good measure use nozzle and water hose to back flush from discharge after I am in the system. Still the issue, aside from an inordinate amount of trouble from March Pumps is the contempt they show toward their customers: IE Me. I was nice until the last e mail, months into the correspondence. Just on this string look at the venom I have for these guys. I am not a hater, but screw me once, Ok, normally I can control it after that. The situations I was put into limited my choices, so now, after this week I want to let people know my story so folks will think twice before spending their money with March.

Bill I close all my thru hulls before a haul out, saves problems on the relaunch. Mule I understand your feelings and would probably feel the same long before I got to the 5th pump. Someone posted the March company info if I was you I'ld contact them directly, good luck.

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Ron on Northern Lights II
I don't like making plans for the day because the word "premeditated" gets thrown around in the courtroom.

Even closing my thru hulls doesn't always ensure I will keep the pump primed. They as in "AC pumps" are strange animals since they push or circulate water and really don't draw water or to use a better example self prime. My dual AC set up with the single March pump was the original Mainship factory installation. The pump is below the water line but above the thru hull entry point.
I always hated squeezing into the ER to prime the AC pump. If I kept the boat I was going to install a diverter valve that would have simply opened up one of the 2 output lines at the pump so I could avoid pulling one of the hoses and waiting until I got a steady stream of water flowing.
Bill

Despite the problems Larry and Mule have had, March is the most reliable pump for small air conditioners on the market. That's why they are standard equipment on most new air conditioner systems.

I am disappointed in the customer service Mule has gotten from March.
Mule, you should try going directly to March with your problem.

I would like to know exactly which model of March pump is failing for you guys.

They did have a batch of them that would over heat fifteen or twenty years ago, but I haven't seen that happen in a very long time.

For larger systems you can't beat the Oberdorfer 104M or 109M pumps.

I would like to know exactly which model of March pump is failing for you guys.

They did have a batch of them that would over heat fifteen or twenty years ago, but I haven't seen that happen in a very long time.

Both the March and Oberdorfer are sensitive to air lock. They should be mounted below the waterline with the hose running continuously up hill from the seacock to the pump intake. A way to burp the system can be useful.

The Oberdorfer fails in an interesting way. If the intake is restricted, the impeller cavitates and vacuum bubbles form and collapse on the pump housing. These bubbles will actually eat craters in the bronze and in extreme cases eat through the housing. When I first saw it I thought it was electrolysis but the cavities formed are different and a factory rep told me what was happening.